The Role of Xylem Hydraulics in Post-fire Tree Physiology

Forest fires of low and moderate intensity often do not constitute a direct lethal threat to mature trees, but rather may leave behind trees with a variety of injuries, subsequently affecting their physiology. Post-fire physiological processes and linking specific heat injuries to impairments of whole-tree functioning are the focus of intense current research. Recent studies suggest that, besides cambium and phloem necrosis, also fire-induced xylem dysfunction plays an important role in post-fire tree physiology.

We analyzed the importance of bark insulation for the protection against fire-induced impairments of tree hydraulics and integrated potential hydraulic dysfunctions into a conceptual framework, which explains post-fire physiological processes, their interactions and possible feedbacks. Further, we monitored stem diameter variations and basal area increments of injured trees in the years after a fire to understand the effects of heat-initiated hydraulic limitations on tree functionality and growth.

Considering climate-driven changes in fire activity, knowledge on post-fire tree responses will become increasingly important to better estimate respective ecosystem dynamics and interactions with other disturbances such as drought events or biotic attacks.

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Andreas Bar